This chapter examines issues related to the radicalization of individuals. It explores the advent of terrorism studies. Early scholars laid the foundations for current thinking on terrorism. The chapter defines radicalization as the process wherein participants are drawn into a protest with the likelihood of a terrorist act taking place. The classic definition of radicalization has been much contested from its very beginning. The 9/11 attacks of Al-Qaeda gave terrorism studies a renewed boost. The chapter looks into various models which depict the steps of radicalization. It also looks at the factors which make an individual become a terrorist: conductive environment, opportunity, local mobilization hubs, and ideology. In most cases, the process of socialization into extremism and terrorism transpires gradually.